Did you know gypsum patches are not permitted in fire-rated gypsum wall assemblies?

By Gus Gonzalez, IFC Technical Consultant

Fire-rated gypsum wall assemblies play a crucial role in safeguarding buildings and occupants from the devastating effects of fire. These assemblies are meticulously designed and tested to meet stringent fire safety standards. Fire-rated gypsum wall assemblies are constructed using specialized materials that have been tested and certified to resist the spread of fire for a specified period. These assemblies typically consist of gypsum board, stud, insulation, and other components engineered to provide a barrier against the passage of flames, and smoke. One common misconception in the industry is the use of gypsum patches on fire-rated gypsum wall assemblies.

In some instances, builders and contractors may be tempted to use gypsum patches to repair or modify sections of a fire-rated wall assembly. Gypsum patches involve the application of additional gypsum material to address imperfections, damage, or to close off oversized openings for penetrations. While gypsum is a fire-resistive material, using patches can compromise the integrity of the entire wall system. Any modification to the wall assembly, including the use of gypsum patches to attempt to reduce the size of an opening in the wall, will alter the intended performance and compromise the fire rating. Building codes and regulations strictly mandate adherence to tested designs to ensure the reliability of fire protection systems (see IBC Section 703).

Below are examples of gypsum patches being used. The addition of fire sealant around the perimeter of the patches does nothing to restore the rating of the assembly as this is not how the fire-rated wall assembly was tested.

Damaged gypsum wall assemblies can be repaired following the methods outlined by the Gypsum Association guide GA-225 instructions (Repair of Fire-Rated Gypsum Panel Product Systems). The guide instructs that a new gypsum panel/patch must be mechanically secured to blocking and screwed on all four sides. The new patch is to be flush with the existing wall assembly and finished with mud and tape.

You may also find penetration firestop systems that utilize gypsum patches as part of their design; W-L-1093 for example, but these are far and few. In this case, the penetration firestop system was tested with the gypsum patch in a precisely detailed installation. Therefore the patch is part of the W-L-1093 system used to restore the rating of the wall assembly and not part of the wall itself.

In cases where a large patch-like solution for a fire-rated gypsum wall assembly would be a significant help, such as to reduce the size of a large opening, there are tested and listed solutions that provide proven and known fire resistance ratings, and which therefore would meet code. Those involve what most firestop product manufacturers refer to as “composite sheets/boards”. These firestop products are thin rigid boards that are made of a sandwich of sheet metal, intumescent material, and other materials. These must be installed in strict conformance to the details stated in their individual firestop system listings. A common use for firestop composite sheets is as part of a listed firestop system for a large wall or floor opening that is designed for the passage of cable trays. ?

In conclusion, the prohibition of gypsum patches/laminates on fire-rated wall assemblies is rooted in the need to maintain the reliability and effectiveness of critical fire protection systems. By understanding and respecting the principles behind these regulations, the construction industry can contribute to creating a safer environment for everyone.